Enhanced separation of toxic Blue BG dye by cloud point extraction with IL as an additive: Effect of parameters, solubilization isotherm and evaluation of thermodynamics and design parameters

Cloud point extraction (CPE) was adopted for removal of Blue BG dye from aqueous solution using tetraethyl ammonium tetrafluoroborate [TEA(BF4)] ionic liquid (IL) as an additive with non-ionic surfactant Triton X-114 (TX-114). The effect of different operating parameters such as temperature, time, concentration of surfactant; IL and dye on extraction of dye have been studied in detail to find out optimum conditions. The extraction efficiency was found to increase significantly with temperature, time, surfactant concentration and IL concentration. A developed Langmuir isotherm was used to compute the feed surfactant concentration required for the removal of Blue BG dye up to an extraction efficiency of 90%. The effect of temperature and concentration of surfactant on various thermodynamic parameters, like change in Gibbs-free energy (ΔG°), change in enthalpy (ΔH°), and change in entropy (ΔS°) were examined. It was found that ΔG° increased with temperature but decreased with surfactant concentration whereas ΔH° and ΔS° increased with surfactant concentration.